CVE-2026-20651: Apple macOS Information Disclosure Flaw

CVE-2026-20651 Overview

CVE-2026-20651 is a privacy vulnerability in Apple macOS caused by improper handling of temporary files. This flaw allows a malicious application to potentially access sensitive user data through insecure temporary file operations. Apple has addressed this issue with improved handling of temporary files across multiple macOS versions.

Critical Impact

Applications may be able to access sensitive user data through insecure temporary file handling, potentially exposing private information to unauthorized processes.

Affected Products

• macOS Sequoia versions prior to 15.7.5
• macOS Sonoma versions prior to 14.8.4
• macOS Tahoe versions prior to 26.3

Discovery Timeline

• 2026-03-25 - CVE-2026-20651 published to NVD
• 2026-03-25 - Last updated in NVD database

Technical Details for CVE-2026-20651

Vulnerability Analysis

This vulnerability stems from improper temporary file handling in macOS (CWE-377: Insecure Temporary File). When applications create temporary files without adequate security controls, they may inadvertently expose sensitive user data to other processes on the system. The vulnerability requires local access to exploit, meaning an attacker would need to execute a malicious application on the target system.

The attack can be performed without user interaction or special privileges once the malicious application is running. The primary impact is on confidentiality, as attackers could read sensitive user data that was improperly stored or accessed through temporary files.

Root Cause

The root cause of CVE-2026-20651 is classified as CWE-377 (Insecure Temporary File). This weakness occurs when an application creates temporary files in an insecure manner, such as using predictable file names, creating files in world-readable locations, or failing to properly restrict file permissions. In this case, macOS system components did not adequately protect temporary file operations, creating a path for unauthorized data access.

Attack Vector

The attack vector for this vulnerability is local, requiring the attacker to have the ability to execute code on the target macOS system. A malicious application could exploit this vulnerability by:

1. Monitoring predictable temporary file locations
2. Reading temporary files created by other applications before they are deleted
3. Exploiting race conditions in temporary file creation to access sensitive data

The vulnerability does not require any user interaction once the malicious application is installed and running. No special privileges are needed beyond standard application execution rights.

Detection Methods for CVE-2026-20651

Indicators of Compromise

• Unusual file access patterns in /tmp, /var/folders, or other temporary directories
• Applications attempting to read temporary files they did not create
• Suspicious processes monitoring temporary file creation events
• Unexpected access to user-specific temporary directories by unauthorized applications

Detection Strategies

• Monitor file system access to temporary directories for anomalous read operations
• Implement endpoint detection rules for applications accessing files outside their expected scope
• Use application sandboxing detection to identify processes attempting to escape containment
• Deploy file integrity monitoring on sensitive temporary file locations

Monitoring Recommendations

• Enable detailed file system auditing on macOS systems using Unified Logging
• Configure endpoint protection solutions to alert on suspicious temporary file access patterns
• Monitor for applications with unusual temporary file handling behaviors
• Review system logs for evidence of data exfiltration through temporary file exploitation

How to Mitigate CVE-2026-20651

Immediate Actions Required

• Update macOS Sequoia to version 15.7.5 or later
• Update macOS Sonoma to version 14.8.4 or later
• Update macOS Tahoe to version 26.3 or later
• Review installed applications and remove any untrusted software
• Enable Gatekeeper and ensure only notarized applications can run

Patch Information

Apple has released security updates to address this vulnerability. The patches improve the handling of temporary files to prevent unauthorized access to sensitive user data. Detailed information is available in the following Apple Security Advisories:

• Apple Security Advisory #126348
• Apple Security Advisory #126350
• Apple Security Advisory #126795

Workarounds

• Restrict application installations to only trusted sources via Gatekeeper
• Limit user permissions to reduce the attack surface for local exploitation
• Use application sandboxing to contain potentially vulnerable or malicious applications
• Consider implementing additional endpoint protection solutions that monitor for data access anomalies

# Verify macOS version to ensure patched version is installed
sw_vers -productVersion

# Enable Gatekeeper to restrict untrusted applications
sudo spctl --master-enable

# Check Gatekeeper status
spctl --status